Cutting operations such as grooving and parting off are typically performed by a cutting insert retained in an insert pocket located between upper and lower jaws of a relatively narrow holder blade. The holder blade is, in turn, generally clamped in a blade retaining block. The holder blade is generally provided with an aperture, or a slot, or a slot terminating in an aperture, for resilient displacement of one of the holder blade's jaws relative to the other. For example, in U.S. Pat. No. 4,588,333 a key with two cross-pins is provided. In order to remove the insert one pin is inserted behind the insert in the insert pocket and the other pin is positioned on the top side of the holder body. The insert is pushed out of the pocket by turning the key. In U.S. Pat. No. 5,697,271 a key with a pair of prongs is provided. The clamping jaw is resiliently coupled to the body portion of the holder blade. A cutting insert can be inserted or removed by displacing the clamping jaw relative to the base jaw. In accordance with one embodiment, the clamping jaw is displaced with respect to the base jaw by positioning the prongs within a pair of apertures and turning the key.
The above referenced prior art, as well as other prior art using a similar key mechanism, require that the key be positioned at the side of the holder blade. However, there are many applications, especially when several holder blades are mounted in parallel, where there is not sufficient space to position the key at the side of the holder blade. PCT publication no. WO 97/17154 describes a way of overcoming this problem by employing a bending tool used from the front of a holder blade for displacing the clamping jaw relative to the base jaw.
The present invention proposes a novel approach for overcoming the problem of insufficient space for the positioning of a key on the side of a holder blade.